Electric switch and fabricated frames therefor



May 30, 1933. H, P, PIN HAM 1,912,221"

ELECTRIC SWITCH AND FABRICATED FRAMES THEREFOR Filed April 2, 1930 2Sheets-Sheet 1 fnverfior'. P PM 07 May 30, 1933. p K 1,912,221

ELECTRIC SWITCH AND FABRICATED FRAMES THEREFOR Filed April 2, 1930 2Sheets- Sheet 2 Patented May 30, 1933 UNITED STATES PATENT OFFICE,

HENRY P. PINKHAM, OF WOLLASTON, MASSACHUSETTS, ASSIGNOR TO CONDIT ELEC-TRICAL MANUFACTURING CORPORATION,

CORPORATION OF MASSACHUSETTS OF SOUTH BOSTON, MASSACHUSETTS, A

ELECTRIC SWITCH AND FABRICATED FRAMES THEREFOR Application filed April2,

This invention relates to oil immersed electric switches and to theoilcontaining enclosing casing therefor.

In the usual high tension electric switch the switchmembers areseparated under a body of oil which is enclosed in a casing thatcomprises an open top oil receptacle and a switch frame that constitutesa cover for the open top of the receptacle and provides a rigid supportfor the switch members and the switch operating mechanism. Heretoforethe oil receptable has been made of sheet metal preferably of sheetsteel and the switch frame has been made as acasting, usually of castiron, although for large switches cast steel has been. employed. Whenthe switch is opened under heavy load, considerable gas is evolved atthe switch contacts under the oil and oil is thrown violently upagainstthe cover and thus is thrown outside the switch through any openings oropen joints that may be present in the casing. Such throwing of oil ishighly undesirable. Thus with the usual switch construction theconfronting surfaces I of the oil receptacle and the switch frame havebeen machined to provide plane contacting surfaces in an attempt toprovide" oil tight joints therebetween. Inasmuch as thecastingcomprising the switch frame has a strong tendency to warp afterit has been machined it is exceedingly difficult to maintain the jointtight as the'machined surface will become warped and distorted. Thus, itwill leave open passages through. which the oil can be expelled.Furthermore, when large production and speedy deliveries are involvedthe cast switch frame becomes an expensive proposition. due to the factthat much machine work is'n'ecessary, involving the use of skilledlabor, irregular shapes have to bemachined, and a considerable number(if machined switch frames have to be rejected as defective by reason ofbeing warped and for numerous other reasons. Furthermore, a cast switchframe when subjected to strong internal pressures is liable to burst,instead of merely yielding under the pressure, and thereby renders theswitch useless. Consequently an object of the pres- 1930. Serial No.440,942. I

ent invention is the provision of'an oil immersed switch having a switchframe which is so constructed that it has surfaces that can be'madepractically oil tight without being machined, that has practically notendency to Warp and thereb distort such surfaces, that is adapted toyield instead of burst when subjected to unusually high pressures, andthat can be made at considerably less cost than a cast switch frame.

In addition to the above enumerated defects a cast switch framefrequently has pores which are hard to detect without elaborate andexpensive tests. The presence of pores is highly objectionable,especially 'in a switch of the outdoor type, since they leak water intothe interior of the switch and thereby reduce the dielectric strength.and arc-interrupting properties of the oil and thus seriously impair theeffective operation of the switch and may cause it to fail under smallloads.

A further object of the invention is the provision of a switch framethat is niade from dense or pore-free metal and especially rolled andpressed metal wherein the various )arts constituting the switch frameare welded togetherinto an integral. unit.

A further object of the invention is the provision of a switch framehaving a dome which is formed of pressed metal, an outstandingsupporting flange of sheet metal at the base of the dome and which iswelded thereto, and a depending receptacle-enclosing apronalso of sheetmetal which is dis posed under and is welded to the flange. A switchframe thus constructed is superior to a cast metal switch frame in manyrespects. It is cheaper to make. The dimenvariable treatment of thepattern when making the sand mould. The rolled plates provide smoothflat surfaces that do not require machining to provide oil tight joints.The' rolled plate from which the parts are made has a fibrous structureinstead of a crystalline structure as with cast metal and so will yieldand stretch when subjected to unusual internal pressures instead ofbursting as will a cast switch frame.

A further object of the invention is generally to improve theconstruction and operation of electric switches.

.Fig. 1 is a side elevation of an electric switch embodying theinvention.

i Fig. 2 a plan view of the switch top of the invention.

Fig. 3 is a longitudinal sectional elevation of Fig. 2.

Fig. l is a plan view of the base plate.

Fig. 5 is a sectional detail taken along line 55 Fig. 2.

As herein shown the switch embodying the invention includes a switchframe, or top. 10 which is adapted to receive therewithin and provide acover for the open top of an oil receptacle 12 which herein iselliptical. The switch frame 10 provides a support for a pair ofstationary switch members including the insulating bushings 14 and thecentral conducting studs 16 which extend through the top wall of saidswitch frame and depend therebelow into said oil receptacle 12 and whichare provided at their lower ends with the usual stationary contactmembers, not shown. Said switch frame further provides an uppermechanism compartment within which is enclosed the switch o ierating'mechanism for reciprocating the usual movable switch member. not shown.into and out of engagement with the fixed contact members to close andopen the circuit through the switch.

The switch frame 10. with which this invention is particularlyconcerned, includes a top or dome 18, an outstanding supporting plate orflange 20. and a depending apron 22. all of which are formed ofrelatively thick rolled sheet metal, preferably steel.

The dome 18 is formed from a flat plate. preferably boiler plate, and ispressed between dies into the shape shown, which provides an upstandingside wall 24 which bounds an elliptical area. and a top consisting oftwo flat sections 26 which are inclined slightly upward and meet at theridge 28 which extends transversely across the middle of the dome. Theflat sect-ions each have a circular hole 30 punched therethrough,preferably after pressing the sheet into dome-shape, to admit a switchterminal bushing 14-. Drilled and tapped holes 32 are subsequentlyformed in the sections. around said bushing-holes. to receive bolts Setwhich secure the flanges 36 of the bushings against the flat outer facesof the sections. The pressing operation provides the sections with outerfaces which are suffieientlv plane and true to provide oil tight jointsbetween the sections and the flanges without the necessity for machiningthe faces when the usual paper or other packing discs 38 are locatedunder the flanges.

A hole 40 is formed in the ridge 28 to admit a tool for adjusting theelevation of the movable switch member and said hole is closed by apressed metal plate 42 which has angularly related sides that straddlethe ridge and is welded or is otherwise secured thereto and has anopening 44 which registers with an upstanding pipe nipple 46 welded tothe plate and closed by the removable cap 48. The plate also carriesdepending rods 50 which extend through holes in the ridge and constituteguides for the movable switch member, not shown.

The flange 20 is formed of a flat steel plate and preferably is ofrectangular shape and has an elliptical opening 51 in the middle thereofwhich is smaller than the open end of the dome and also of the oilreceptacle. The bottom edge of the dome is seated on the top of theflange and is equally spaced from the opening 51 so that the flangeprovides an inwardly directed horizontal shelf 52 that is continuousaround the inner periphery of the dome. The dome and the flange areintegrally united by welding by either are or gas flame, the weldingmaterial 54 being applied preferably around the junction between theouter surfaces of the dome flange.

The flange 20 also outstands beyond the outer surface of the dome andupstanding gusset plates 56 of triangular shape are welded to theopposite outstanding ends of the flange and to the upstanding wall ofthe dome to provide additional rigidity to the plate thereatsince theswitch usually is supported on frame members 58 which engagetheunderside of the flange under said gusset plates.

The apron 22 is formed from a steel plate and is rolled or shaped intoendless elliptical form and is located against the under face of theflange 20 in line with the upstanding side wall of the dome and iswelded to the flange, thus being made integral with the flange and dome.Triangular gusset plates 60 are welded to the outer faces of the flangeand apron for strengthening both at the points where the bolts 62, whichattach the oil receptacle to the switch frame, pass through the flange.The apron surrounds the side wall of the oil receptacle at the open topthereof and provides a support therefor which prevents the side wallthercat from being bulged outwardly by an unusually high pressure withinthe casing.

The receptacle 12 is provided with an internal channel 64 at the top inwhich a packing 66 is received which engages the iiiwardly directedshelf 52 of the flange to provide an oil. tight seal between the oil.receptacle and the flange. Since the flange 1s formed from a flat rolledsheet, the lower face thereof is sufficiently true to provide a tightjoint with the packing without being machined.

Various accessory parts are also welded onto the switch frame. Bosses 68are welded onto the inner faces of the flat sections of the dome, aroundthe bushing-openings therethrough, to provide attaching means forcurrent transformers, not shown, which surround the bushings, when suchare used. The switch operating mechanism includes a straight operatingshaft 70, one end of which is shown in Fig. 1, and which extendsentirely through openings in the opposite faces of the upstanding wallof the dome. Bearing blocks 72 for the shaft are located within the domeand rest upon the shelf 52 of the frame and are welded thereto and tothe dome. lVeather-protecting casings 74 for the ends of the shaft,comprising the tubular necks 76 and outer outstanding flanges 78 havetheir necks welded to the outer faces of the upstanding side wall of thedome. Pipe nipples 80 are welded onto the upstanding side wall of thedome to provide passages through which the leads of the currenttransformers are extended. An elbow 82 is also welded to the side wallto provide a convenient means for filling the switch with oil or forventing the switch.

The switch frame thus constructed is strong and rigid and is free fromlarge surfaces that have to be machined and thus is considerably cheaperto make, especially in large quantities, than a cast metal frame.

lVhile the invention is particularly effective in connection with theelliptical type of switch frame here shown, as elliptical surfaces areconsiderably more difficult to machine than circular or rectangularsurfaces, the invention is also effective for other shapes.

The switch frame construction here shown is also shown and described inmy (o-pending application Serial No. 450,463, filed May 7, 1930.

I claim:

1. A fabricated top-frame for electric switches comprising an invertedterminalsupporting dome having a side wall which surrounds an openbot-tom, a plate under said dome against the end of said side wall andhaving an opening therein within and conforming in general to thecontour of said side wall and having bracket-constituting portions thatextend outwardly beyond said side wall, and means securing said dome andplate together.

2. A fabricated top-frame for electric switches comprising an invertedterminalsupporting dome having a side wall which surrounds an openbottom, a plate under said dome against the end of said side wall andhaving an openingtherein within and conforming in general to the contourof said side wall and having bracket-constituting portions that extendoutwardly beyond said side wall, a tank-encircling flange locatedbeneath said dome and plate and seated on the latter and encircling theopening in the plate, and means securing said dome, plate and flangetogether. a

3. A fabricated top-frame for, electric switches comprising an invertedterminalsupporting dome having a side wall which surrounds an openbottom, a plate under said dome against the end of said side wall havingan opening therein within and conforming in general to the contour ofsaid side wall and having bracket-constitutin portions that extendoutwardly beyond sai side wall, a tank-encircling flange located beneathsaid dome and plate and seated on the latter and encircling and spacedbeyond the opening in the plate, and means securing said dome, plate andflange together.

4. A fabricated top-frame for electric switches comprising an invertedterminalsupporting dome having a side wall which surrounds an openbottom, a plate under said dome against the end of said side wall andhaving an opening therein which is spaced a substantial distance fromand conforms in general to the contour of said side wall, whereby toconstitute a continuous tank-seat within the boundary of said dome, saidplate having bracket-constituting portions that extend outwardly beyondsaid side wall, and means securing said dome and plate together.

5. A fabricated top-frame for electric switches comprising an invertedterminalsupporting dome having a side wall which surrounds an openbottom, a plate under said dome against the end of said side wall andhaving an opening therein which is spaced a substantial distance fromand conforms in general to the contour of said side wall, whereby toconstitute a continuous tank-seat within the boundary of said dome, saidplate having bracket-constituting portions that extend outwardly beyondsaid side wall, a tank-encircling flange located beneath said dome andplate and seated on the latter and spaced from and encircling saidplate-opening, and means securing said dome, plate, and flange together.

6. A fabricated top-frame for electric switches comprising aninvertedterminal.- supporting dome having a side wall which surrounds anopen bottom, a plate under said dome against the end of said side walland having an opening therein which is spaced a substantial distancefrom and conforms in general to the contour of said side wall, wherebyto constitute a continuous tank-seat within the boundary of said dome,

said plate having braeket-constituting p01- tions that extend outwardlybevund said side wall, a tank-encircling flange located beneath saiddome and plate and seated on the latter and spaced from and encirclingsaid plate-opening, means securing' said dome. plate and flangetogether, and shaft hearing blocks seated on and secured to the upperface of: said tank-seat on opposite sides of said opening.

I11 testimony whereof, I have signed my name to this specification.

' HENRY P. PIN KHAM.

